Cranial Neuropathies

What are cranial neuropathies?

Nerves power your entire body. But those nerves can be damaged by injury or an illness such as diabetes. Neuropathy is a disorder of nerve damage. It affects your ability to feel and move. Exactly how your body and your movement are affected depends on where in the body the damaged nerves are located. When nerves in the brain or brainstem are affected, it is called cranial neuropathy.

The cranial nerves are those that arise directly from your brain or brainstem. They often affect areas like the face and eyes. Some of the different types of cranial neuropathies are:

Microvascular cranial nerve palsy. This health problem affects 1 or more nerves, typically those that go to the eye. It is most common in people who have diabetes and high blood pressure.

Third nerve palsy. This condition affects the third cranial nerve. This nerve helps manage muscles that control eye movement, as well as the size of the pupil.

Fourth nerve palsy. This is also called superior oblique palsy. It affects the superior oblique muscle, which helps you converge your eyes (to look at the tip of your nose).

Sixth nerve palsy. This is also called cranial nerve VI or abducens palsy. It affects the sixth cranial nerve, which also helps control eye movement.

If several different cranial nerves are affected, it is called multiple cranial neuropathies (MCN).

What causes cranial neuropathies?

Cranial neuropathy can develop for many different reasons. These include:

Infections. Infections in the spinal fluid can irritate cranial nerves. For example, Lyme disease often affects the seventh nerve. But it can cause problems with any cranial nerve.

Cancer. Cancer cells can spread to the spinal fluid and damage one or more cranial nerves. Sometimes cancer can press on cranial nerves as they run through the skull.

Increased intracranial pressure from a tumor, head trauma, or brain swelling. This can injure cranial nerves. Pressure can also be raised in certain headaches. Cranial nerves 3, 4, and 6 are most often affected.

Congenital cranial neuropathies. These are nerve injuries from trauma that occurs at birth. Or they can occur before birth from developmental problems or infection.

Microvascular cranial nerve palsy. This can develop in people who have high blood pressure or other vascular risks, such as diabetes or smoking. Poor circulation to the cranial nerves injures them. It most often affects cranial nerves 3, 4, and 6.

Autoimmune abnormalities. These occur when the immune system attacks one's own cranial nerves. This can happen in Guillain-Barre syndrome or lupus.

Aneurysm. This can press on nearby nerves. It most often affects cranial nerves, 3, 4, and 6.

What are the symptoms of cranial neuropathies?

Different types of neuropathies can cause different symptoms. They are based on which nerves are damaged and where they are located. Generally, neuropathies can cause:

Pain

A tingling sensation

Numbness

Skin that feels sensitive to the touch

Weak or paralyzed muscles. This can cause drooling or slurred speech.

Vision changes

Some of the symptoms of different types of cranial neuropathies include:

Bell palsy can cause drooping of part of the face. It usually only affects one side of the face.

Electromyography (EMG), which measures the electrical activity of muscles when working and at rest

CT or MRI scans, which are imaging tests that allow healthcare providers to see the brain

Nerve conduction velocity tests to help find out how and where the nerve is damaged

Biopsies of the skin and nerves to find out how severely nerves are damaged

Hearing tests

Spinal tap (lumbar puncture) to look for infection or inflammation in the spinal fluid

Angiography, a special X-ray that uses contrast dye and takes pictures of your heart and blood vessels

How are cranial neuropathies treated?

A cranial neuropathy could be the sign of a life-threatening emergency. It should be assessed by a healthcare provider right away. Many types of cranial neuropathies will get better with time, without any treatment. Sometimes medicines can be used to treat an infection, help reduce swelling in or near a nerve, or help if the neuropathy is causing pain. For some types of neuropathies and in some cases, surgery may help. Other times, the nerve damage can't be treated or fixed.

But it's important to diagnose and treat any health conditions that are causing the neuropathy. Treating common causes like high blood pressure, infections, and diabetes can help to treat the neuropathy. Eating nutritious foods, avoiding smoking, and limiting alcohol can also help manage neuropathy.

Can cranial neuropathies be prevented?

Cranial neuropathy can't always be prevented. But controlling common causes can help to reduce the risk of developing neuropathy. You can:

Reduce your risk factors for stroke and head injury

Manage your diabetes well, if you have the disease

Lower your blood pressure, if needed

Living with cranial neuropathy

Cranial neuropathies are often not dangerous. They may get better on their own with time. But they can certainly be bothersome for the people who have them.

Your best strategy for managing a cranial neuropathy is to manage possible causes. These include diabetes, high blood pressure, infections, and brain tumors. You should also prevent head injury.

If the symptoms do not go away on their own, your healthcare team might recommend physical therapy, occupational therapy, or other options to help with them. Talk with your healthcare provider about other possible options, such as surgery, if a cranial neuropathy is affecting your quality of life.

When should I call my healthcare provider?

If you have been diagnosed with a cranial neuropathy, talk with your healthcare providers about when you might need to call them. They will likely advise you to call if your symptoms get worse or if you develop new symptoms such as pain, numbness, weakness, or changes in vision.

Key points about cranial neuropathies

Cranial neuropathies are caused by damage to one or more cranial nerves. These are nerves that arise directly from the brain. They affect movement and feeling in the eyes and face.

The causes of cranial neuropathies include poorly controlled diabetes or high blood pressure, head injuries, infections, strokes, and brain tumors.

Common symptoms can include weakness or loss of sensation in part of the face, or changes in vision.

Some cranial neuropathies go away on their own. But others might be permanent. Controlling diabetes and high blood pressure can sometimes help. If symptoms do not go away, medicines, surgery, or other treatments might be helpful as well.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

Know the reason for your visit and what you want to happen.

Before your visit, write down questions you want answered.

Bring someone with you to help you ask questions and remember what your provider tells you.

At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.

Ask if your condition can be treated in other ways.

Know why a test or procedure is recommended and what the results could mean.

Know what to expect if you do not take the medicine or have the test or procedure.

If you have a follow-up appointment, write down the date, time, and purpose for that visit.